Pharmaceutical compounds (PhCs) are contaminants of emerging environmental-health concern that, if not checked, could adversely affect drinking water sources and wastewater reuse projects, two key issues of sustainable water management. To develop water reuse and ensure the preservation of drinking water supplies in Europe, it is thus important to eliminate these compounds duringwastewater treatment. Wastewater treatment plants (WWTPs) are crucial barriers against PhCs, but many of these compounds are resistant to conventional treatments. In the logic of resource efficiency, cost-effective solutions based on existing infrastructure (many of them recently built) are essential, as new investments are limited in the near future due to economic constraints.
The LIFE Impetus project aimed to demonstrate measures for improving PhC removal in urban WWTPs with conventional activated sludge (CAS) treatment. As CAS is the most common biological process in urban WWTPs, the solutions may be easily transferred to wastewater treatment plants across Europe. The project planned to carry out a three-year field test in two Portuguese CAS-WWTPs in water-stressed regions (Lisbon and Algarve). This included assessing and improving the WWTPs performance, using benchmarking tools and chemical enhancement measures easily implemented in current treatment lines. Theproject thus aimed at providing, for several European wastewater quality scenarios, guidelines for reliable and sustainable improvement of PhC removal in conventional WWTPs with minimum energy consumption. New adsorbents made from local vegetal wastes (e.g. carob and cork) and coagulants were compared with commercial products. A complementary objective was to produce valuable knowledge for water resource protection and associated environmental policy, including PhC occurrence and concentration, PhC control in WWTPs, and bioaccumulation in clams, a key product in Algarve and elsewhere in Europe.
LIFE Impetus demonstrated technical solutions for improving the removal of pharmaceuticals (PhCs) in urban wastewater treatment plants (WWTPs) with conventional activated sludge (CAS) treatment. These were shown to be easily implemented in current CAS-WWTPs and adjustable to wastewater quality variations, with low investment, low energy consumption, and using renewable eco-materials. The project team implemented two innovative technical solutions: i) operating strategies to enhance biological treatment for PhC removal, and ii) addition of powdered activated carbon (PAC) to the biological reactor, using eco-friendly adsorbents, to control recalcitrant PhCs. Extensive monitoring and field testing was conducted in two Portuguese CAS-WWTPs of different sizes and CAS reactor types: Beirolas WWTP, near Lisbon, discharging into the Tagus River, ca. 50 000 m3/d (anaerobicanoxicoxic process); and Faro NW WWTP, in Faro (Algarve), discharging into Ria Formosa lagoon, 5 000 m3/d (oxidation ditch type). Up to 908 wastewater (and 72 sludge) samples were analysed for 24 PhCs/hormones found in wastewater. 150 clam samples were also analysed in the Algarve to assess PhC bioaccumulation. The clam species Ruditapes decussatus was found to be a suitable bio-indicator of PhC bioavailability in water environments.
Several compounds were shown to be below their quantification limit at the WWTPs inlets, others presented intermediate and variable removals, but two compounds (carbamazepine and diclofenac) were found to be recalcitrant with almost unchanged concentrations. To assess the impact of adding PAC to the biological reactor, two doses (10 and 25 mg/L) were applied to Faro NW WWTP. With 10 mg/L, a decrease in most compounds was obtained, most noteworthy high reductions of the antibiotics erythromycin, sulfamethoxazole and sulfapyridine, of atenolol and other beta-blockers , and of carbamazepine and diclofenac (the latter two hardly eliminated without PAC addition). With 25 mg/L, the results generally pointed to greater PhC reduction and higher reliability.
These results, including a cost-benefit analysis, demonstrated improved control of PhCs in conventional wastewater treatment, with little additional cost investment, energy consumption or indirect greenhouse gas (GHG) emissions. In fact, costs of PAC addition to bioreactor are lower than those of technology-intensive solutions (e.g. PAC, GAC, ozone, and membrane post-treatments) particularly for low plant capacity. In turn, by maximising energy efficiency and improving treated water quality, cost savings potential from CAS-operation improvement (related with WWTP discharge fee) amounted to 5 854 /year in Beirolas and 2 069 /year in Faro NW WWTPs.
Environmental and health benefits derive from the improved removal of PhCs, and the production of improved treated water quality, including water colour, turbidity, transmittance and organic matter. In terms of social benefits, the project trained technicians and helped create jobs, contributing to better informed professionals involved in water and PhCs decision-making and education. During the project, six qualified workers were hired, four of which resulted in permanent positions.
Specific contributions have already been provided towards EU policy on water protection and water reuse. The project knowledge on emerging contaminants and safe control barriers is influencing the Portuguese position with respect to the ISO wastewater reuse standards. Besides, in the LIFE Waste-Water Treatment Platform Meeting, the project team shared their findings and outcomes with industry and key players in EU water policy, responsible for the ongoing revision of the EU urban wastewater treatment directive (UWWTD).
The project outcomes have good demonstration value and huge replicability potential, as activated sludge (CAS) treatment is the most common biological process in urban WWTPs in Portugal and worldwide. The project beneficiaries produced technical guidelines, comprising best practices and lessons learned. An important unexpected project result was the production of a new pine nut shell-derived, physically activated PAC, which outperforms the best commercial PAC tested and is already under pre-industrial production. This new pine nut shell-derived PAC provides an opportunity for companies, including Millipore/Sigma, to develop green activated carbons from local vegetable wastes.
Further information on the project can be found in the project's layman report (see "Read more" section).